Sudden cardiac death

Sudden cardiac death is a rare but devastating event. The majority of cases in young athletes are caused by congenital cardiac abnormalities that are routinely clinically silent before causing sudden death. An optimal screening practice to help identify underlying asymptomatic cardiac abnormalities has met with much debate. Beyond the American Heart Association's recommendations for cardiovascular screening guidelines for the preparticipation physical examination [47], there are conflicting views regarding the use of more advanced diagnostic screening tests. Athletes in whom a potentially life-threatening cardiovascular abnormality is found face the probability of being restricted from participating in certain types of athletic activity. Participation guidelines for athletes with cardiovascular disease are detailed in the recommendations of the 26th Bethesda Conference [36]. Future goals should continue to focus on the prevention of SCD. The development of a cost-effective screening process that incorporates the use of echocardiography, although having its own set of inherent limitations, may prove to be the most viable option.     

Preparticipation cardiovascular screening

Regular aerobic exercise provides many health benefits regardless of age, and should be promoted by health care providers to all patients. In older athletes, coronary artery disease is the most common cause of sudden death. There is widespread consensus, however, that the overall health benefits derived from exercise outweigh the risks of participation. Screening should focus on identifying signs and symptoms of underlying cardiovascular disease by obtaining a personal and family history and performing a focused physical examination according to the recommendations of the AHA. Exercise testing is recommended in males older than 40 and females older than 50, and individuals with cardiac risk factors. Cardiovascular PPE screening in young athletes remains a challenge, because potentially fatal abnormalities are uncommon and in some cases are undetectable without sophisticated testing. Most sudden cardiac deaths in athletes are caused by anomalies that are clinically silent, are rare, or are difficult to detect by history and physical examination. Many athletes may not experience symptoms consistent with heart disease or may not report family histories of sudden cardiac death. Important clues to a cardiac abnormality include history of syncope, chest pain, and family history of sudden death. Any underlying condition suspected on the basis of history or physical examination requires further diagnostic evaluation before the athlete can be cleared for activity. Currently there is considerable variability and inconsistency among state requirements for PPEs. A national adoption of a more uniform PPE screening process should be encouraged. The screening process should include the AHA's cardiovascular screening recommendations, as this would assist in closing the gap between screening practices recommended by sports medicine experts and the reality of current screening practices. Although the extent of screening continues to be debated, clinical guidelines for performing PPEs and determining clearance have been established. Without a uniform implementation of the current guidelines, it will not be possible to assess the value of the current cardiovascular screening recommendations in detecting and preventing cardiovascular death in young athletes. Physicians should be aware of the emerging role of genetic testing for cardiovascular diseases in athletes with a family history of heart disease or sudden death. Advances in the diagnosis and understanding of cardiovascular disease may provide better tools for preventing sudden death of young athletes in the future [11].     

Hypertrophic cardiomyopathy: who plays and who sits

Hypertrophic cardiomyopathy (HCM) is a genetically determined, primary myocardial disease associated with an increased risk for sudden cardiac death during physical exertion. In the United States, HCM is the most frequent cause of exertion-related sudden cardiac death (SCD). Current recommendations provided by the 26th Bethesda Conference entitled Recommendations for Determining Eligibility for Competition in Athletes with Cardiovascular Abnormalities restrict participation for patients with HCM to sports requiring low levels of dynamic and isometric exertion. Such recommendations are prudent given the association of the disease with disastrous cardiovascular consequences. Nevertheless, because the prognosis of HCM and its risk of sudden death is typified by great variability among patients, these recommendations may be overly restrictive for many patients with this disease, and it is possible that a subset of low-risk patients can be identified who may continue to engage in more vigorous exercise activities. This article presents our current understanding and approach to evaluating and advising athletes with HCM.     

Screening young athletes for prevention of sudden cardiac death: Practical recommendations for sports physicians

Regular intensive exercise in athletes increases the relative risk of sudden cardiac death (SCD) compared with the relatively sedentary population. Most cases of SCD are due to silent cardiovascular diseases, and pre‐participation screening of athletes at risk of SCD is thus of major importance. However, medical guidelines and recommendations differ widely between countries. In Italy, the National Health System recommends pre‐participation screening for all competitive athletes including personal and family history, a physical examination, and a resting 12‐lead electrocardiogram (ECG). In the United States, the American College of Cardiology and the American Heart Association recommend a pre‐participation screening program limited to the use of specific questionnaires and a clinical examination. The value of a 12‐lead ECG is debated based on issues surrounding cost‐efficiency and feasibility. The aim of this review was to focus on (i) the incidence rate of cardiac diseases in relation to SCD; (ii) the value of conducting a questionnaire and a physical examination; (iii) the value of a 12‐lead resting ECG; (iv) the importance of other cardiac evaluations in the prevention of SCD; and (v) the best practice for pre‐participation screening.     

Sudden death and physical activity in athletes and nonathletes

Among young athletes, sudden deaths are predominantly associated with cardiomyopathies, coronary artery abnormalities and myocarditis, but coronary heart disease is a reality already in this group. The absolute risk of sudden death is, however, low and the benefits of routine medical screening are small. If an athlete has had any symptoms that arouse suspicion of cardiac disease, the athlete must be meticulously investigated, as an underlying life-threatening illness may be present. Among all nonathletes, as well as athletes ≥30 years, the predominant cause of sudden death is coronary heart disease. A large number of studies have provided strong evidence suggesting the benefits of physical activity regarding prevention of cardiovascular death and disease. The immediate risk for sudden death is higher during physical activity than during other times, especially among usually sedentary individuals, but inactivity is much more dangerous in the long run. Regular exercise at moderate intensity gives large benefits with small risks. The benefits of irregular and intensive exercise are less clear and the risks higher. For the individual without known heart disease who exercises regularly, the risk for sudden death during physical activity is extremely small.     

Electrocardiograms in athletes: interpretation and diagnostic accuracy

PURPOSE: Electrocardiography (ECG) has been proposed as a method to enhance the ability of the preparticipation examination (PPE) to detect underlying cardiac conditions that can lead to sudden cardiac death (SCD) in young athletes. METHODS AND RESULTS: We conducted a Medline review of the published medical literature, using the key terms of cardiovascular screening of athletes, ECG in athletes, SCD in athletes, and ECG in specific cardiac disease states: hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, dilated cardiomyopathy, myocarditis, long QT syndrome, Brugada syndrome, coronary artery anomalies, myocardial bridging, aortic stenosis, mitral valve prolapse, and Marfan syndrome. ECG seems to increase the sensitivity of the PPE from 2.5-6% to 50-95%. Overall sensitivity appears to be about 50%; false-positive rates can be as high as 40%, and there is at least a 4-5% false-negative rate. In Europe, ECG-based screening programs have been associated with a decline in the SCD rate in young athletes, but similar programs are currently not recommended in the United States for many reasons: lack of randomized trial data; cost of screening; lack of a clear standard for ECG interpretation in the athlete; the likelihood that asymptomatic athletes with underlying lethal conditions might differ significantly from symptomatic individuals with the same conditions; and concern that ECG screening might actually increase the death rate, via treatment-related procedural complications. CONCLUSIONS: Although some authorities advocate the use of ECG screening of young athletes, further studies are required to define what constitutes a normal ECG in athletes, and to determine whether ECG-based screening protocols truly are superior, not only in finding disease, but also saving lives. For those who either choose ECG-based screening or interpret ECG in athletes, we propose a simple interpretation scheme and decision tree.     

Sudden death in competitive athletes

Sudden death in athletes is an extremely rare event yet no less tragic for its infrequency. Up to 90% of these deaths are due to underlying cardiovascular diseases and therefore categorized as sudden cardiac death (SCD). The causes of SCD among athletes are strongly correlated with age. In young athletes (<35 years), the leading causes are congenital cardiac diseases, particularly hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and congenital coronary artery anomalies. By contrast, most of deaths in older athletes (<35 years) are due to coronary artery disease. This review focuses on the cardiac causes of SCD and provides a brief summary of the principal noncardiac causes. Current pre-participation screening strategies are also discussed, with particular emphasis on the Italian experience.     

Cardiac issues in the young athlete

Young athletes are disproportionately plagued with congenital cardiac disease. Many of these diseases predispose to sudden cardiac death (SCD), a dramatic and tragic outcome for any young athlete. In many cases, conditions that predispose to SCD do not cause symptoms or show signs on examination, making diagnosis of cardiac disease and prevention of SCD difficult. Clinicians should be familiar with common causes of SCD and their symptoms, perform careful evaluations, refer athletes in whom there are concerns, and make sure any concerning findings receive thorough evaluation. Clinicians should also be familiar with and follow recent guidelines on return to play. Unfortunately, most preparticipation examinations are inadequate, due in part to use of inadequate forms. Better forms are available and should replace inadequate ones.     

Electrocardiography and the preparticipation physical examination: Is it time for routine screening?

The preparticipation physical examination (PPE) is a screening tool endorsed by numerous organizations and used to evaluate young athletes prior to competition for both medical and musculoskeletal conditions that may predispose them to injury. The cardiac portion of the examination, as recommended by the American Heart Association, is detailed specifically to detect signs or symptoms consistent with certain congenital heart conditions that may increase a young athlete’s risk of sudden cardiac death (SCD). Much controversy has erupted over the years as to whether this examination has the diagnostic sensitivity to detect these conditions and prevent SCD, and whether additional modalities, such as the 12-lead electrocardiograph (ECG), should be incorporated. Given the rarity of SCD events, the large population of young athletes that would qualify yearly for the examination, and the limitations that an ECG would present, it would not be efficient to add the ECG to the standard PPE on the symptomatic athlete. More efforts should be spent in standardizing the PPE on a national level to further improve its efficiency.     

Practical recommendations and perspectives on cardiac screening for healthy pediatric athletes

Primary care providers often are asked to perform the preparticipation physical exam and cardiac screening of pediatric athletes. It can be challenging to evaluate which athletes may require further cardiac evaluation and specialist referral based on a focused history and physical. There is considerable controversy surrounding mass electrocardiogram (ECG) screening of athletes in the United States. The ECG is one of several diagnostic tests used by pediatric cardiologists in the evaluation of underlying heart disease in young athletes. This article reviews cardiac conditions associated with sudden death, discusses pertinent findings on history and physical, and provides clinically relevant information for practitioners who are deciding which patients to refer for detailed cardiac evaluation.     

Cardiovascular screening of athletes.

Cardiovascular screening of athletes is a challenging aspect of the preparticipation evaluation. While sudden cardiac death in young athletes is uncommon, preparticipation screening may identify some predisposing conditions that place individuals at increased risk. The most common pre-existing cardiac abnormalities in athletes causing sudden death in the United States are hypertrophic cardiomyopathy, congenital coronary anomalies, and Marfan syndrome. Preparticipation cardiovascular screening should pursue any history of cardiac symptoms or family history of premature cardiac disease, as well as abnormal cardiovascular physical findings. Positive findings should be investigated; an electrocardiogram, echocardiogram, or consultation with a specialist should be considered. Recommendations are then available to guide athletic participation according to the cardiovascular diagnosis.     

The electrocardiographic early repolarization pattern in athletes: normal variant or sudden death risk factor?

The clinical evaluation of athletes during symptom evaluation or pre-participation screening often involves interpretation of the 12-lead electrocardiogram (ECG). Differentiating abnormal ECG findings suggestive of underlying cardiovascular disease from benign findings caused by exercise-induced cardiac adaptations can be challenging, and recent clinical guidelines have been created for this purpose. One of the most common ECG findings in athletes is the early repolarization pattern (ERP), characterized by diffuse J-point elevation and concave ST-segment elevation, and long regarded as a normal variant. However, recently published data suggest that the ERP may be a marker of increased risk for sudden cardiac death (SCD) in the general population. The observation that the ERP can indicate increased SCD risk has important implications for the clinician charged with the care of athletes. This review will describe the evolving understanding of the ERP and will explore the relevance of the ERP for the care of athletes.     

The prevalence and clinical significance of premature ventricular beats in the athlete

Adolescents and adults with cardiovascular disease who are engaged in sports activity have an increased risk of sudden cardiac death (SCD) that is three times greater than that of their non-athletic counterparts. Sport acts as a trigger for cardiac arrest in the presence of underlying cardiovascular diseases predisposing to life-threatening ventricular arrhythmias. Frequent and complex premature ventricular beats (PVBs) detected during the cardiovascular screening of the athletic population may be a sign of an underlying cardiovascular disease at risk of SCD, but are also often recorded in trained athletes without cardiovascular abnormalities. Thus, the interpretation of PVBs could represent a clinical dilemma, particularly in the athlete. However, while some characteristics of PVBs can be considered common and benign, others occur uncommonly in the athletic population and raise the suspicion of an underlying cardiovascular disease. This review discusses the prevalence and clinical significance of PVBs in the athlete, with a focus on exercise-induced PVBs, on the analysis of PVB's morphology at 12-lead ECG, and on the morphological substrates identified by imaging techniques. The implications on eligibility for competitive sports participation are also discussed, according to the relevance of PVB detection for disqualifying athletes from competitions.     

Cardiac MRI and CT features of inheritable and congenital conditions associated with sudden cardiac death

Cardiac MRI (CMR) and electrocardiogram (ECG)-gated multi-detector computed tomography (MDCT) are increasingly important tools in the identification and assessment of cardiac-related disease processes, including those associated with sudden cardiac death (SCD). While the commonest cause of SCD is coronary artery disease (CAD), in patients under 35 years inheritable cardiomyopathies such as hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy are important aetiologies. CMR in particular offers both accurate delineation of the morphological abnormalities associated with these and other conditions and the possibility for risk stratification for development of ventricular arrhythmias with demonstration of macroscopic scar by delayed enhancement imaging with intravenous gadolinium.     

Mandatory ECG screening of athletes: is this question now resolved?

European and North American cardiologists have long debated the need for mandatory ECG screening of athletes in order to prevent sudden cardiac death. European investigators have recently adduced new evidence, which they believe supports the need for such screening. They note a decrease of sudden cardiac deaths among Italian athletes following the introduction of mandatory screening in that country, clearer definitions of resting ECG abnormalities in athletes, new and more encouraging calculations of cost/benefit ratios and direct comparisons of clinical examination alone against clinical examination plus ECG screening. Nevertheless, it seems that critical criteria for the success of any screening procedure (a substantial prevalence of the problem, coupled with an adequate test sensitivity and specificity) have yet to be satisfied. Very few athletes are liable to sudden cardiac death, only a few of those who are vulnerable will be identified by ECG screening, and even if all potential cases could be detected, restriction of their physical activity would be unlikely to have a major influence on their prognosis. At the same time, a requirement of mandatory testing would discourage engagement in physical activity, and would impose substantial direct costs on the community. Moreover, the large number of false positive test results could have important and undesirable consequences for both indirect medical costs and the overall health of competitors. ECG screening might become more effective if it could be focused on a smaller sub-group of vulnerable athletes, or if the problem of false positive tests could be addressed through an increase of test specificity. However, on the basis of current information, it would seem better to direct efforts in preventive medicine to more common causes of premature death in the young adult.     

Acute cardiac emergencies in the injured athlete

In the previous discussion, emphasis has been placed on the detection of cardiac disorders that might lead to sudden death. Cardiac crises result from congenital structural defects in athletes aged 35 years or younger, and from acquired diseases in older individuals. Detection implies preparticipation screening, which, in order to be effective, requires considerable financial resources impractical for community-wide athletic programs. In young asymptomatic individuals, the prevalence of congenital heart disease is estimated at 0.5 per cent. Perhaps 1 per cent of these athletes has congenital lesions that could potentially result in sudden death and of these, only 10 per cent will, indeed, die suddenly. Identification of a group of 1000 athletes who have congenital cardiovascular disease of whom perhaps only one will die suddenly requires screening of 200,000 competitors. It is rather unlikely that any community would consider this type of undertaking economically feasible, especially considering that the most useful test for the younger age group, the echocardiogram, is also one of the most expensive. Noninvasive screening on an individual basis, in most instances, will identify those athletes at risk for sudden death if appropriate financial resources can be applied. History and physical examination, chest roentgenogram, 12-lead electrocardiogram, echocardiography, and exercise stress testing are useful tools in the recognition of those conditions associated with acute cardiac emergencies.     

Marfan syndrome: screening for sudden death in athletes

Marfan syndrome is a common, preventable cause of sudden cardiac death in the athlete. It is an autosomaldominant disorder of connective tissue with variable penetration that affects multiple organ systems. Aortic root aneurysm rupture or dissection is the most common cause of sudden death. A directed family and personal history, in addition to a search for characteristic physical stigmata, can optimize the screening of athletes during the preparticipation evaluation. Athletes who have pertinent findings on the preparticipation evaluation should undergo further diagnostic evaluation. Echocardiography is essential to rule out cardiovascular involvement in those suspected of having Marfan syndrome, and should be mandated when positive pertinent family or personal history is elicited or when cardiac abnormalities are detected. Fortunately, due to characteristic historic and clinical findings, Marfan syndrome can be detected early, allowing appropriate treatment and ultimately prevention of sudden death in affected athletes.     

Sudden cardiac death in young athletes: time for a Nordic approach in screening?

In 2005, the European Society of Cardiology published recommendations for cardiovascular screening in athletes. Discussion on whether screening is beneficial is ongoing. Recently, the first prospective results on effectiveness of screening in preventing sudden deaths were published from Italy. The results were supportive of screening, but did not provide conclusive evidence. Our suggestion for a Nordic approach on this issue is a directed cardiovascular examination initially involving elite athletes, because this is feasible with respect to the Nordic health care systems and the organization and logistics of elite competitive sports, but also because of the negative aspects of screening large populations. This directed cardiovascular examination would include personal and family history, clinical examination, and electrocardiography (ECG). Further examinations should thereafter be carried out in athletes with suggestive findings in the initial evaluation. The directed cardiovascular examination should be voluntary. It should be conducted at least once, with information on alarming symptoms (syncope, chest pain or dizziness during exercise) and heredity (sudden cardiac death or hereditary heart disease in near relatives) stressed to the athlete as indications for necessary check-ups in the future. The examination would also provide the athlete with an ECG recording, which is valuable as a reference at a later time.     

Cardiovascular pre-participation screening of young competitive athletes for prevention of sudden death in China.

The cardiovascular pre-participation screening proposal for young competitive athletes has the potential to save young lives. This study aimed to identify individuals at risk for potentially lethal cardiovascular diseases in athletes before competition. Between June 2005 and July 2005, 351 (170 male and 181 female) elite Chinese athletes from 21 sports were profiled. The 12-lead electrocardiogram and echocardiography were employed to evaluate cardiovascular diseases. The vast majority had no definitive evidence of cardiovascular disease. However, abnormal ECGs were identified in 16 athletes (4.5%), including 4 with distinctly abnormal and 12 with mildly abnormal patterns. Only 13 athletes (3.7%) had echocardiographic evidence of relatively mild valve regurgitation that had not been previously suspected. In three athletes with relatively mild ventricular septal hypertrophy (13-14 mm), it was not possible to discern with absolute certainty whether the wall thickening was a manifestation of hypertrophic cardiomyopathy or secondary to athletic conditioning ("athlete heart"). This screening protocol identified no athletes with definite evidence of hypertrophic cardiomyopathy, Marfan's syndrome or other cardiovascular diseases that convey a significant potential risk for sudden death or disease progression during athletic activity. This is largely due to the relative low prevalence of conditions resulting in sudden cardiac death in young athletes and high false positive/negative rates in the tests used as part of the screening process (due to a large overlap between cardiovascular changes due to pathology and those due to intense training).     

Common issues in sports cardiology

Many cardiac conditions found in athletes are amenable to athletic participation if well-managed. As always, a respect for the causes of sudden cardiac death in athletes is paramount. Although rare, sudden cardiac death in athletes is frequently preventable by careful pre-participation screening. The authors hope that more athletes will undergo screening, and that basic investigations, including but not limited to electrocardiography, will become more widespread. A high degree of surveillance for cardiac pathology in athletes is the duty of any sports medicine practitioner.